Functional diversity of subgroup 5 R2R3-MYBs promoting proanthocyanidin biosynthesis and their key residues and motifs in tea plant

The tea plant(Camellia sinensis)is rich in polyphenolic compounds.Particularly,flavan-3-ols and proanthocyanidins(PAs)are essential for the flavor and disease-resistance property of tea leaves.The fifth subgroup of R2R3-MYB transcription factors comprises the primary activators of PA biosynthesis.This study showed that subgroup 5 R2R3-MYBs in tea plants contained at least nine genes belonging to the TT2,MYB5,and MYBPA types.Tannin-rich plants showed an expansion in the number of subgroup 5 R2R3-MYB genes compared with other dicotyledonous and monocot plants.The MYBPA-type genes of tea plant were slightly expanded.qRT–PCR analysis and GUS staining analysis of promoter activity under a series of treatments revealed the differential responses of CsMYB5s to biotic and abiotic stresses.In particular,CsMYB5a,CsMYB5b,and CsMYB5e responded to high-intensity light,high temperature,MeJA,and mechanical wounding,whereas CsMYB5f and CsMYB5g were only induced by wounding.Three genetic transformation systems(C.sinensis,Nicotiana tabacum,and Arabidopsis thaliana)were used to verify the biological function of CsMYB5s.The results show that CsMYB5a,CsMYB5b,and CsMYB5e could promote the gene expression of CsLAR and CsANR.However,CsMYB5f and CsMYB5g could only upregulate the gene expression of CsLAR but not CsANR.A series of site-directed mutation and domain-swapping experiments were used to verify functional domains and key amino acids of CsMYB5s responsible for the regulation of PA biosynthesis.This study aimed to provide insight into the induced expression and functional diversity model of PA biosynthesis regulation in tea plants.

Basal internode elongation of rice as affected by light intensity and leaf area

Short basal internodes are important for lodging resistance of rice(Oryza sativa L.).Several canopy indices affect the elongation of basal internodes,but uncertainty as to the key factors determining elongation of basal internodes persists.The objectives of this study were(1)to identify key factors affecting the elongation of basal internodes and(2)to establish a quantitative relationship between basal internode length and canopy indices.An inbred rice cultivar,Yinjingruanzhan,was grown in two split-plot field experiments with three N rates(0,75,and 150 kg N ha−1 in early season and 0,90,and 180 kg N ha−1 in late season)as main plots,three seedling densities(16.7,75.0,and 187.5 seedlings m−2)as subplots,and three replications in the 2015 early and late seasons in Guangzhou,China.Light intensity at base of canopy(Lb),light quality as determined from red/far-red light ratio(R/FR),light transmission ratio(LTR),leaf area index(LAI),leaf N concentration(NLV)and final length of second internode(counted from soil surface upward)(FIL)were recorded.Higher N rate and seedling density resulted in significantly longer FIL.FIL was negatively correlated with Lb,LTR,and R/FR(P<0.01)and positively correlated with LAI(P<0.01),but not correlated with NLV(P>0.05).Stepwise linear regression analysis showed that FIL was strongly associated with Lb and LAI(R2=0.82).Heavy N application to pot-grown rice at the beginning of first internode elongation did not change FIL.We conclude that FIL is determined mainly by Lb and LAI at jointing stage.NLV has no direct effect on the elongation of basal internodes.N application indirectly affects FIL by changing LAI and light conditions in the rice canopy.Reducing LAI and improving canopy light transmission at jointing stage can shorten the basal internodes and increase the lodging resistance of rice.

Epinephrine promotes tumor progression and M2 polarization of tumor-associated macrophages by regulating the TRIM2-NF-kB pathway in colorectal cancer cells

Tumor-associated inflammation is an important component of the tumor microenvironment,and an important factor affecting tumor progression.In the tumor microenvironment,tumor-associated macrophages(TAMs)receive different stimuli and can be polarized into classically activated M1 macrophages and alternatively activated M2 macrophages.Many studies have indicated that the polarization of TAMs is closely related to tumor progression.